Chain saw attachment for use in trimming shrubbery

ABSTRACT

An attachment for a chain saw (100) includes two elongated members (4D) mountable on the opposite faces of the chain guide (102). Each member (4D) has an elongated center portion (6D) configured to be secured to the chain guide (102) in a position closely adjacent to the corresponding face thereof. An angled portion (30) extends laterally outwardly from the outer edge of the center portion (6D). A plurality of spaced apart teeth (12D) project from the angled portion (30) substantially parallel to the chain guide (102) over and beyond the chain (104). Each tooth (12D) has, on an upstream edge thereof, a surface (18D) angled laterally outwardly in an upstream direction to help retain the chain on a path around the periphery of the chain guide (102). The angled surface (18D) is preferably formed by bending the edge of a substantially flat tooth. The surface (18D) preferably extends along the tooth (12D) from its pointed tip portion (36) to and along a radiused junction (34) with the angled portion (30) of the elongated member (4D).

RELATED APPLICATION

This application is a continuation-in-part of U.S. patent applicationSer. No. 08/538,499, filed Sep. 29, 1995and soon to be issued as U.S.Pat. No. 5,560,111.

TECHNICAL FIELD

This invention relates to chain saw attachments and, more particularly,to an attachment having first and second elongated members mountable onopposite faces of the chain saw chain guide, each such member having anelongated center portion, an angled portion extending laterallyoutwardly from the center portion, and a plurality of teeth projectingfrom the angled portion parallel to the chain guide past the chain, andsaid teeth having angled surfaces angled laterally outwardly in anupstream direction to help retain the chain on a path around the chainguide.

BACKGROUND INFORMATION

Professional and amateur landscaping and gardening frequently requirestrimming hedges, shrubs, and small trees. This task is commonly carriedout using manual clippers and/or powered hedge trimmers. The use ofmanual clippers is tiring and very time consuming. A typical hedgetrimmer helps to speed the trimming process but is capable of cuttingonly small twigs and foliage. Even small branches generally require anadditional tool. A chain saw is powerful enough to cut branches of allsizes but is not often used in its basic form for trimming operationsbecause of safety considerations and difficulty in engaging flexibleshoots and small twigs to be cut by the chain. Attachments for chainsaws designed for use in trimming operations are disclosed in U.S. Pat.Nos. 2,642,901, granted Jun. 23, 1953, to E. A. Hayden; No. 2,698,034,granted Dec. 28, 1954, to E. A. Jakku; No. 2,797,717, granted Jul. 2,1957, to J. H. Budd; No. 3,808,684, granted May 7, 1974, to Robert L.Ludwig; U.S. 4,142,292, granted Mar. 6, 1979, to Ray R. Ulrich; and U.S.5,123,168, granted Jun. 23, 1992, to William E. Lyons.

SUMMARY OF THE INVENTION

The present invention is directed toward an attachment for a chain sawof a type having an elongated chain guide with opposite faces bounded bya periphery, and an endless chain powered by a motor to move around saidperiphery. According to an aspect of the invention, the attachmentcomprises first and second elongated members mountable on the oppositefaces. Each elongated member includes an elongated center portion, anelongated angled portion, and a plurality of spaced apart teeth. Thecenter portion is configured to be secured to the chain guide in aposition closely adjacent to the corresponding face thereof. The angledportion extends laterally outwardly from an edge of the center portionand forms an acute angle with the chain guide. The teeth are positionedto project from the angled portion substantially parallel to the chainguide over and beyond the chain. Each tooth includes, on an upstreamedge of the tooth, relative to the motion of the chain about the chainguide, an angled surface angled laterally outwardly in an upstreamdirection to help retain the chain on a path around the periphery.

In the currently preferred form, each tooth has a main portion that hassubstantially parallel opposite edges. The main portion extends from aradiused junction with the angled portion to a pointed outer tipportion. The angled surface extends along an upstream one of theopposite edges and an upstream portion of the radiused junction.

The angled surface of the tooth may be formed in various ways.Preferably, each tooth is substantially flat, and the upstream edge isbent laterally outwardly to provide the angled surface. An alternativeto this preferred configuration is an upstream edge that is beveled toprovide the angled surface.

An optional feature is the provision of spacers between the teeth. Whenthe elongated members are mounted on the opposite faces of the chainguide, the teeth are arranged in opposite confronting pairs. The teethin each pair are substantially parallel to each other. A spacer extendsperpendicularly between the teeth in each pair to inhibit bending of theteeth toward the chain. The spacers may be formed in various ways. Forexample, each spacer may comprise a pin extending between and attachedto the teeth in the corresponding pair.

The number of teeth may be varied. The teeth may be positioned all theway around the working portion of the chain or only around a portionthereof. For example, the teeth could be omitted from one of thelongitudinal edges of the chain guide and/or the rounded tip of thechain guide. Preferably, the teeth are arranged in two rows extending inopposite directions from the angled portion so that there is a row ofpairs of teeth along each of the longitudinal edges of the chain guide.Additional teeth may be provided on the rounded end of the chain guide,preferably with sufficient space therebetween to permit cutting oflarger branches.

The attachment of the invention provides a convenient and cost effectivemeans for converting a standard chain saw into a trimming tool capableof carrying out a variety of trimming operations. Such operationsinclude cutting various types of vegetation from pliant shoots to smallbranches. The teeth in the attachment help to protect the user fromcontact with the cutting chain. They also serve to capture pliantvegetation to position it for cutting and to control the direction inwhich cut vegetation moves. The combination of the center portionclosely adjacent to the chain guide and the angled portion provides astable interface between the attachment and the chain guide and helpsensure that each tooth along the length of the attachment is maintainedin its proper spaced relationship relative to the chain.

The angled surface on the upstream edge of each tooth helps to retainthe chain on its proper path around the periphery of the chain guard.With use, the endless chains of chain saws have a tendency to loosen,which can lead to their disengagement from the track around theperiphery of the chain guide. The angled surface on the attachment teethprovides a guide for the chain when it deviates from its path and tendsto guide the chain back into its proper path. It also helps alert theuser to the need for tightening the chain when nicks and scratches beginto appear on the angled surface.

In the preferred embodiment, the elongated member, including its angledportion and the angled surfaces of the teeth, can be die cut from apiece of sheet metal. This allows quick and low cost manufacture of theattachment.

The optional feature of a spacer between the tip portions of the teethincreases the stability of the attachment structure and enhances theaction of the elongated ribs in maintaining the teeth properly spacedaway from the chain. It also helps to prevent bending of the teeth andconsequent damage to the attachment.

These and other advantages and features will become apparent from thedetailed description of the best mode for carrying out the inventionthat follows.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, like element designations refer to like partsthroughout, and:

FIG. 1 is a pictorial view of an attachment mounted on a chain saw andbeing used to trim a shrub.

FIG. 2 is a pictorial view of the chain saw and attachment shown in FIG.1.

FIG. 3 is an elevational view of one of the faces of the chain guideshown in FIGS. 1 and 2 and the attachment member mounted thereon.

FIG. 4 is a view of the chain guide and attachment shown in FIGS. 1-3,looking toward a longitudinal edge of the chain guide.

FIG. 5 is a sectional view taken along the line 5--5 in FIG. 4.

FIG. 6 is an enlarged pictorial view of the front rounded end of thechain guide and attachment shown in FIGS. 1-5.

FIG. 7 is like FIG. 6 except that it shows a modified form of theattachment shown in FIGS. 1-6.

FIG. 8 is a fragmentary view like a portion of FIG. 4 except that itshows another embodiment of the angled surface feature of theattachment.

FIG. 9 is like FIG. 4 except that it shows another modified form of theattachment.

FIG. 10 is a sectional view taken along the line 10--10 in FIG. 9.

FIG. 11 is like FIGS. 6 and 7, but shows the attachment shown in FIGS. 9and 10.

FIG. 12 is a view like FIGS. 6, 7, and 11, showing still anothermodification of the front tip portion of the attachment.

FIG. 13 is a fragmentary pictorial view of the currently preferredembodiment of the invention installed on a chain guide.

FIG. 14 is a fragmentary elevational view of one of the elongatedmembers shown in FIG. 13.

FIG. 15 is a sectional view taken along the line 15--15 in FIG. 13.

BEST MODE FOR CARRYING OUT THE INVENTION

The drawings show attachments that embody various aspects and featuresof the invention. FIGS. 13-15 show an embodiment that is constructedaccording to the invention and that constitutes the best mode forcarrying out the invention currently known to the applicant. Theattachment is designed for use with a standard chain saw, such as thechain saw 100 shown in the drawings and particularly in FIGS. 1 and 2.The illustrated chain saw 100 is of a type having an elongated flatchain guide 102 with opposite faces bounded by a periphery. Theperiphery is conventionally provided with a channel 103 that receives anendless chain 104. A motor 106 powers the chain saw 100 to move thechain 104 around the periphery of the chain guide 102. The chain 104moves along a path defined by the channel 103. The chain saw 100 isprovided with two handles 108, 110 to be gripped by the user, asillustrated in FIG. 1. In FIG. 1, the chain saw 100 is shown in what isanticipated will be a typical use position for trimming a shrub S.

A first embodiment of the attachment 2 is shown in FIGS. 1-6. Theattachment 2 comprises first and second elongated members 4, which arepreferably mirror images of each other. Each member 4 has an elongatedcenter portion 6 and a plurality of spaced apart teeth 12 projectingfrom the center portion 6. The two opposite members 4 are mountable onthe opposite faces of the chain guide 102, as shown in FIGS. 1-6. Eachmember 4, including its teeth 12, has a flat plate-like configurationwith an elongated rib 8 extending along the inner flat surface of thecenter portion 6 that is adjacent to the chain guide 102 when theattachment 2 is installed on the chain saw 100. The rib 8 has anelongated flat configuration to provide a firm abutting surface betweenthe attachment member 4 and the chain guide 102 extending along at leastmost of the length of the chain guide 102. The rib 8 may be formedseparately from the flat plate-like main portion of the member 4, or theentire member 4, including its center portion 6, rib 8, and teeth 12,may be integrally formed.

The two members 4 are attached to the chain guide 102 by means offasteners, such as the bolts 10 shown in the drawings. In most cases,two bolts 10 are sufficient to secure the attachment 2 to the chainguide 102. Each bolt 10 extends through the center portion 6 of eachmember 4, including the rib 8 extending therealong. It also extendsthrough an aligned hole in the chain guide 102. The hole in the chainguide 102 may be a preexisting hole or may be drilled by the personinstalling the attachment 2 on the chain saw 100.

The rib 8 has a flat rectangular outer surface positioned to abut theface of the chain guide 102 on which the member 4 is mounted. ideally,abutment would occur throughout the entire outer surface of the rib 8.However, minor irregularities in the face of the chain guide 102 and theouter surface of the rib 8 are, as a practical matter, unavoidable.Therefore, the abutment between the two surfaces is partial, withportions of the outer surface of the rib 8 being closely adjacent to,rather than in abutment with, the chain guide 102. Preferably, the bolts10 are tightened to maximize the area of abutment between the chainguide 102 and the ribs 8.

The teeth 12 project outwardly from the center portion 6 of the member 4substantially parallel to the chain guide 102 over and beyond the chain104. The projecting of the teeth 12 beyond the chain 104 helps protectthe user against contact with the chain 104 and also helps to holdfoliage in position to be cut by the chain 104. Since the teeth 12 areformed as extensions of the flat plate-like portion of the member 4, thepresence of the rib 8 serves to space the teeth 12 laterally away fromthe chain 104. This prevents the attachment 2 from interfering with themovement of the chain 104 about the chain guide 102. As shown in FIGS.1-6, the arrangement of teeth 12 includes two rows of teeth 12 extendingin opposite directions from the center portion 6 of each elongatedmember 4. It also includes two teeth 22 at the forward tip of the chainguide 102 arranged at an angle that provides greater spacing between thetwo forward teeth 22 than between the teeth 12 in the parallel rows toallow larger branches to be cut with the tip of the chain saw 100.

The teeth 12 are provided with angled edges in order to help retain thechain 104 on its path through the channel 103 around the periphery ofthe chain guide 102. As shown in FIGS. 1-6, the angled surface 18 isprovided on the upstream edge of each tooth 12, 22, relative to themotion of the chain 104 about the chain guide 102. The arrow in FIG. 4indicates the direction of motion. The surface 18 is angled laterallyoutwardly in an upstream direction so that it tends to guide the chain104 back into its path should a portion of the chain 104 move out of theperipheral channel 103 on the chain guide 102. The surface is preferablyat an angle of about 45° to the direction of motion. Referring to FIGS.1-6, in the embodiment of the attachment 2 illustrated therein, theangled surface 18 is formed by providing a substantially flat tooth 12,22 with an upstream edge that is bent laterally outwardly to provide thesurface 18. This tooth configuration has the advantages of accomplishingthe desired angled surface guide while maintaining simplicity ofconstruction and easy manufacture.

Another feature of the invention is the provision of spacers to inhibitbending of the teeth toward the chain 104. Still referring to FIGS. 1-6,in the illustrated embodiment, the teeth 12, 22 are arranged in oppositeconfronting pairs when the members 4 are mounted on the opposite facesof the chain guide 102. Each pair of teeth 12, 22 includes one tooth 12,22 of each member 4, with the two teeth 12, 22 being substantiallyparallel to each other. The spacer 16 extends perpendicularly betweentip portions of the teeth 12, 22 in each pair.

As shown in FIGS. 1-6, the spacer 16 may be formed by bending the tipsof the confronting teeth 12, 22 laterally inwardly toward each other.The confronting edges of the bent tips 16 preferably abut each other toprovide resistance to inward bending of the teeth 12, 22. The desiredabutting relationship may be maintained by welding the bent tips 16together. Alternatively, the two bent tips may overlap each other withone tip either abutting the inner face of the opposite tooth or beingsecured to the other tip, by welding, a fastener, or other suitablemeans.

Together, the bent tips 16 form a blunt outer end of the pair of teeth12, 22. In the illustrated configuration, each half of the blunt outerend 16 is integral with its corresponding tooth 12, 22 and elongatedmember 4. The blunt outer end is preferably integral with at least oneof the teeth 12, 22 in the pair. This may be accomplished by the twobent tip arrangement shown in FIGS. 1-6, by forming the entire bluntouter end on one of the teeth, or by forming the two teeth in the pairand the blunt outer end as a single integral stamped metal or moldedplastic piece. Whatever the technique for forming the blunt outer end,each tooth 12, 22 preferably has opposite edge portions 14 that taperinwardly toward each other to the blunt outer end. This tapering of theouter ends of the teeth 12, 22 helps to guide vegetation to be cut intothe spaces between the teeth 12, 22 and into contact with the movingchain 104.

The outer edges of the elongated members 4 between the outer portions ofthe teeth 12, 22 are provided with a bevel 19 (FIG. 3). The bevel 19helps to guide cut vegetation away from the chain 104. The bevel may beformed by a straight angle or by a rounded edge.

FIG. 7 illustrates a modification of the embodiment shown in FIGS. 1-6.Elements of the attachment shown in FIG. 7 corresponding to elements inFIGS. 1-6 have the same reference numeral with the addition of theletter "A". In FIG. 7, the forward teeth 22 shown in FIGS. 1-4 and 6 areomitted to expose a greater end portion of the chain 104 and chain guide102 to enable the cutting of relatively large branches. The elongatedmember 4A has a center portion 6A with essentially the same structure asthat shown in FIGS. 1-6, including the spacing and strengthening rib 8.As shown in FIG. 7, the teeth 12A of the member 4A lack the bentupstream edge 18 shown in FIGS. 1-6. However, they preferably areprovided with upstream angled surfaces to help retain the chain 104 onits path. In other respects, the modified embodiment shown in FIG. 7 issubstantially the same as that shown in FIGS. 1-6.

FIG. 8 illustrates another modification of the embodiment shown in FIGS.1-6. Corresponding elements have the same reference numerals as in FIGS.1-6, with the addition of the letter "B". The modification shown in FIG.8 is found in the structure of the teeth 12B. Instead of the bent tip 16shown in FIGS. 1-7, each tooth 12B has a spacer pin 16B, describedfurther below in reference to FIGS. 9-11. The angled surface is alsoformed differently from that shown in FIGS. 1-6. Referring to FIG. 8,the upstream edge of each tooth 12B is beveled, as at 18B, to providethe angled surface.

Another embodiment of the attachment is shown in FIGS. 9-11. Theelements of this embodiment that correspond to the elements of theembodiment shown in FIGS. 1-6 have the same reference numerals as inFIGS. 1-6, with the addition of the letter "C". Referring to FIGS. 9-11,a pin 16C extends perpendicularly between tip portions of the teeth 12Cand is attached to the these tip portions. The pin 16C forms a spacerfor inhibiting bending of the teeth 12C toward the chain 104, asdescribed above. The pin may be cylindrical, as shown, or may have anyof a variety of other configurations. In this embodiment, there is noblunt outer end on the pair of teeth, and the space between the twoteeth 12C is open except for the presence of the pin 16C. As shown,there also is no angled surface, such as the surfaces 18 and 18B shownin FIGS. 1-6 and 8. However, such a surface is preferably provided incombination with the spacer pin 16C.

FIG. 12 shows a modification of the embodiment shown in FIGS. 9-11. Inthis embodiment, the two forward teeth are replaced by an arcuateforward tip guard 26 that encloses the front end of the chain guide 102.Such a forward tip guard could also be provided on the embodiment shownin FIGS. 1-6. The tip guard 26 has the advantages of increasing theprotection of the user and surrounding objects against unintendedcontact with the chain 104. The corresponding disadvantage is that, whenthis modified attachment is mounted on the chain saw 100, the chain saw100 cannot be used to cut any branch that will not fit between adjacentteeth 12C in the opposite rows of teeth 12C. Thus, the optional tipguard 26 would normally be included only in attachments intended to beused for relatively light duty trimming operations.

FIGS. 13-15 show the currently preferred embodiment of the invention.The elements of this embodiment that correspond to the elements of theembodiment shown in FIGS. 1-6 have the same reference numerals as inFIGS. 1-6, with the addition of the letter "D". Referring to FIGS.13-15, in the preferred embodiment, the lateral spacing of the teeth 12Dis accomplished by an angled portion 30 of the elongated member 4D inplace of the rib 8 shown in FIGS. 1-6. This angled construction ispreferred because it is more economical to manufacture. The entireelongated member 4D may be manufactured by die cutting it from a pieceof sheet metal.

Still referring to FIGS. 13-15, the attachment of the preferredembodiment comprises first and second elongated members 4D, which arepreferably mirror images of each other. The two members 4D are mountableon the opposite faces of the chain guide 102, as shown in FIGS. 13 and15. Each member 4D includes an elongated center portion 6D configured tobe secured to the chain guide 102 in a position closely adjacent to thecorresponding face of the guide 102. The securing of the center portion60 is preferably accomplished by a plurality of bolts 10D, as describedabove in connection with the embodiment of FIGS. 1-6. An elongatedangled portion 30 extends laterally outwardly from the outer edge of thecenter portion 6D and forms an acute angle X with the chain guide 102.The angle X is preferably about 45°. However, as used herein, the term"acute angle" is intended to include angles of less than 45° and rangingtherefrom to angles as large as 90°. A plurality of spaced apart teeth12D project from the outer edge of the angled portion 30 substantiallyparallel to the chain guide 102 over and beyond the chain 104.

Each tooth 12D has a main flat, substantially rectangular portion 32with substantially parallel opposite edges. The main portion 32 isintegrally joined to the angled portion 30 at a radiused junction 34.The tooth 12D also has a pointed outer tip portion 36 with edges thattaper inwardly toward each other from the main portion 32 to a pointedend. An angled surface 18D is formed on the upstream edge of the mainportion 32 of the tooth 12D, relative to the motion of the chain 104about the chain guide 102. The direction of motion of the chain 104 isindicated by the arrow in FIG. 14. Like the angled surface 18 of theembodiment of FIGS. 1-6, the angled surface 18D shown in FIGS. 13-15angles laterally outwardly in an upstream direction to help retain thechain 104 on its path around the periphery of the chain guide 102. Theangled surface 18D preferably extends along the upstream edge from thepointed tip portion 36 to and along the radiused junction 34. The angledsurface 18D is preferably formed by bending the upstream edge of asubstantially flat tooth laterally outwardly. However, the angledsurface could also be formed by a bevel, as in FIG. 8.

The angled portion 30 of the elongated member 4D and the teeth 12D mayextend all the way around the working portion of the chain 104 or only aportion thereof. For example, the teeth 12D, or the teeth 12D and theangled portion 30, could be omitted from one of the longitudinal edgesof the chain guide 102 and/or the rounded tip of the chain guide 102, asin FIG. 7. Alternatively, in place of teeth on the tip of the chainguard 102, a tip guard like the one in FIG. 12 could be provided.Preferably, on each elongated member 4D, the teeth 12D are arranged intwo rows extending in opposite directions from the angled portion 30.The teeth 12D may be arranged in opposite confronting pairs, with theteeth 12D in each pair being substantially parallel to each other. Theattachment may further comprise a spacer extending perpendicularlybetween the teeth 12D in each pair to inhibit bending of the teethtoward the chain 104. The spacer may take the form of a pin, as shown inFIGS. 9-11, the form of the blunt bent tips, as shown in FIGS. 1-6 and7, or some other form.

Another feature that may be provided in the embodiment shown in FIGS.13-15 is a means for adjusting the gap between the teeth 18D. Toaccomplish this, one of the elongated members 4D would be provided withtwo holes for each bolt fastener 10D or, alternatively, with a slot foreach bolt fastener 10D instead of a round hole. Such an arrangementallows the modified elongated member 4D to be moved longitudinallyrelative to the other elongated member 4D to offset it with respect tothe other member 4D. The offset decreases the effective distance betweenadjacent teeth 12D. Attachments with this modification would not includethe spacer feature.

The installation of the attachment of the invention on a chain saw canbe accomplished quickly and easily. The only modification of the chainsaw that may be required is the drilling of one or two holes through thechain guide. For embodiments of the attachment having elongated membersthat are separate from each other, installation simply requirespositioning the two members adjacent to the chain guide faces andinserting and securing the bolts. For embodiments in which the membersare joined to each other, installation is the same except that the twomembers are slid onto the chain guide like a sleeve, rather than beingseparately positioned from the sides. In either case, the attachment maybe removed and reinstalled, as desired.

Although the preferred embodiments of the invention have beenillustrated and described herein, it is intended to be understood bythose skilled in the art that various modifications and omissions inform and detail may be made without departing from the spirit and scopeof the invention as defined by the following claims.

What is claimed is:
 1. An attachment for a chain saw of a type having anelongated chain guide with opposite faces bounded by a periphery, and anendless chain powered by a motor to move around said periphery, saidattachment comprising first and second elongated members mountable onsaid opposite faces; each said member including an elongated centerportion configured to be secured to the chain guide in a positionclosely adjacent to the corresponding face thereof, an elongated angledportion extending laterally outwardly from an edge of said centerportion and forming an acute angle with the chain guide, and a pluralityof spaced apart teeth positioned to project from said angled portionsubstantially parallel to the chain guide over and beyond the chain;each said tooth including, on an upstream edge of said tooth, relativeto the motion of the chain about the chain guide, an angled surfaceangled laterally outwardly in an upstream direction to help retain thechain on a path around said periphery.
 2. The attachment of claim 1,wherein each said tooth has a main portion that has substantiallyparallel opposite edges and that extends from a radiused junction withsaid angled portion to a pointed outer tip portion, and said angledsurface extends along an upstream one of said opposite edges and anupstream portion of said radiused junction.
 3. The attachment of claim2, wherein each said tooth is substantially flat, and said upstream edgeis bent laterally outwardly to provide said surface.
 4. The attachmentof claim 3, wherein, on each said member, said teeth are arranged in tworows extending in opposite directions from said angled portion.
 5. Theattachment of claim 2, in which, when said members are mounted on saidfaces, said teeth are arranged in opposite confronting pairs, with theteeth in each said pair being substantially parallel to each other; andsaid attachment further comprises a spacer extending perpendicularlybetween the teeth in each pair to inhibit bending of the teeth towardthe chain.
 6. The attachment of claim 5, wherein said spacer comprises apin extending between and attached to said teeth in the correspondingpair.
 7. The attachment of claim 2, wherein, on each said member, saidteeth are arranged in two rows extending in opposite directions fromsaid angled portion.
 8. The attachment of claim 1, wherein said upstreamedge is beveled to provide said surface.
 9. The attachment of claim 1,wherein each said tooth is substantially flat, and said upstream edge isbent laterally outwardly to provide said surface.
 10. The attachment ofclaim 9, wherein, on each said member, said teeth are arranged in tworows extending in opposite directions from said angled portion.
 11. Theattachment of claim 1, in which, when said members are mounted on saidfaces, said teeth are arranged in opposite confronting pairs, with theteeth in each said pair being substantially parallel to each other; andsaid attachment further comprises a spacer extending perpendicularlybetween the teeth in each pair to inhibit bending of the teeth towardthe chain.
 12. The attachment of claim 11, wherein said spacer comprisesa pin extending between and attached to said teeth in the correspondingpair.
 13. The attachment of claim 1, wherein, on each said member, saidteeth are arranged in two rows extending in opposite directions fromsaid angled portion.